Fair Value Measurement - Fair Value of Assets (Liabilities) Not Measured at Fair Value In Consolidated Balance Sheets (Details) - USD ($) $ in Thousands |
Mar. 31, 2017 |
Dec. 31, 2016 |
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|---|---|---|---|---|---|---|---|
| Level 1 | Debt Securities | |||||||
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | |||||||
| Fair Value | [1] | $ 0 | $ 0 | ||||
| Level 1 | Long-term Debt | |||||||
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | |||||||
| Long term debt, fair value | [2] | 0 | 0 | ||||
| Level 2 | Debt Securities | |||||||
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | |||||||
| Fair Value | [1] | 0 | 0 | ||||
| Level 2 | Long-term Debt | |||||||
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | |||||||
| Long term debt, fair value | [2] | (366,922) | (368,408) | ||||
| Level 3 | Debt Securities | |||||||
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | |||||||
| Fair Value | [1] | 21,439 | 20,519 | ||||
| Level 3 | Long-term Debt | |||||||
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | |||||||
| Long term debt, fair value | [2] | $ 0 | $ 0 | ||||
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